Induced spawning (ovulation and spermiation) in carp and related species

In fish farms, hormonal induced ovulation and spermiation are commonly performed in carps (Cyprinidae) and related species by hypophysation which consists of direct stimulation of the gonads by administration of crude carp pituitary homogenates. The use of synthetic hypothalamic hormones as luteinizing hormone releasing hormone analogues (LHRHa) seems promising. LHRHa administration is used routinely in China for different species of carps. However, LHRHa treatments are partially efficient in inducing ovulation in female common carp and furthermore, in Chinese carps and tench, the latency of the ovulatory response is delayed when compared to hypophysation. The use of LHRHa treatment combined with pimozide, a dopamine blocking agent, improves these two points. These trials are still at an experimental stage. This paper also reviews other techniques for inducing spawning and which are still at a research stag